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Anatomical MRI study of hippocampus and amygdala in patients with current and remitted major depression
Sheila C Caetano1, John P Hatch, Paolo Brambilla
1Division of Mood and Anxiety Disorders, Department of Psychiatry, University of Texas Health Sciences Center at San Antonio, TX, USA.
Abstract:
Morphometric MRI studies suggest decreased hippocampal volumes in currently depressed patients, with conflicting findings for the amygdala. We studied these temporal lobe structures and superior temporal gyrus (STG) in patients with current and remitted major depression. We scanned 31 unmedicated depressed patients (21 currently depressed, 10 remitted) and 31 matched healthy controls with a 3D SPGR sequence in a 1.5 Tesla GE Signa Imaging System. There was a trend towards smaller left amygdala volumes in all depressed patients compared with healthy controls. We found significantly smaller hippocampal volumes bilaterally in currently depressed patients than in remitted patients. Furthermore, we found a statistically significant inverse correlation between length of illness and left hippocampus volumes and right superior temporal gyrus volumes. Our finding of smaller hippocampi in currently depressed patients is consistent with the hypothesis that hypercortisolism could result in hippocampal neurotoxicity in major depression. A smaller hippocampal size may be more characteristic of the depressive state and not be present in remitted patients.
Insights
Major depression is linked to smaller hippocampal volumes, particularly in currently depressed individuals. Hippocampal size may recover in remission, suggesting it
Area of Science:
- Neuroimaging
- Psychiatry
- Neuroscience
Background:
- Morphometric MRI studies indicate reduced hippocampal volumes in major depression.
- Findings on amygdala volume in depression are conflicting.
- Temporal lobe structures, including the hippocampus, amygdala, and superior temporal gyrus (STG), are implicated in major depressive disorder.
Purpose of the Study:
- To investigate hippocampal and amygdala volumes in patients with current and remitted major depression.
- To examine the superior temporal gyrus (STG) in these patient groups.
- To correlate neuroanatomical findings with illness duration.
Main Methods:
- Magnetic Resonance Imaging (MRI) using a 3D SPGR sequence on a 1.5 Tesla GE Signa scanner.
- Study included 31 unmedicated patients with major depression (21 currently depressed, 10 remitted) and 31 matched healthy controls.
- Volumetric analysis of the hippocampus, amygdala, and STG.
Main Results:
- A trend towards smaller left amygdala volumes was observed in all depressed patients compared to controls.
- Currently depressed patients exhibited significantly smaller bilateral hippocampal volumes than remitted patients.
- A significant inverse correlation was found between illness duration and left hippocampus/right STG volumes.
Conclusions:
- Smaller hippocampal volumes appear characteristic of the active depressive state and may not persist in remission.
- Findings support the hypothesis that hypercortisolism-induced hippocampal neurotoxicity contributes to major depression.
- Hippocampal volume reduction may be a state-dependent marker in major depression.
